Fender piles have the task of elastically absorbing the ramming impact of a ship during berthing and of protecting from damage the ship's hull on the one hand and the quays or other harbour structures on the other hand. It is therefore essential for a fender pile to be elastic on the one hand but to also have sufficiently high strength on the other hand in order to resist the ramming impact.
Apart from the wooden or steel fender piles known from time immemorial, there are also concrete fender piles which are prestressed in their longitudinal direction with steel prestressing members (journal "Concrete International", May 1987, pp. 32-36). Although these known concrete piles fulfill their purpose, they only have a low durability, since the prestressing members, in particular when the fender piles are used in sea ports, are subjected to very severe corrosion due to the effects of the atmosphere and sea water. Since the fender piles are intended to deform during the ramming impact, cracks inevitably occur in the concrete through which water and air and also aggressive gases present herein can reach the prestressing steel members and quickly destroy them. In addition, since the elasticity of the prestressing members made of high-strength steels is limited, the deformation of the pipes under the ramming impact is relatively slight so that the fender piles themselves must have a relatively high strength, in order to be able to absorb the ramming impacts acting on them.